EVALUATION OF GENERAL ANESTHETICS IN RELATION TO TRIGEMINO-AUTONOMIC REFLEX

在成年日本大白兔上，用乌拉坦和α-氯丙酮麻醉，观察了全麻药对电刺激三叉神经诱发的三叉神经抑制反应(TDR)的影响。气管插管，股动脉插管。根据股动脉压力波计算动脉压和心率。用10s的方波脉冲序列(0.5ms)刺激精神神经。在初步研究中，我们确定了诱发三叉神经降压反应的最佳频率和强度范围为5 Hz和5-20 mA。在本研究中，以这种方式刺激精神神经。我们观察了两种挥发性麻醉剂(异氟烷和七氟烷)和一种静脉麻醉剂(异丙酚)。在异氟醚和七氟醚中，血压下降的程度随着麻醉药吸入浓度的增加而减小。TDR几乎在0.75-1.0MAC(尾钳法)中消失。1.0MAC法相当于Guedel‘s临床征象中第三阶段的3或4平面。提示异氟醚和七氟烷抑制TDR所需的浓度较高，而异丙酚对TDR的影响较小。在极高剂量的125 mg/kg/hr给药剂量下，可观察到约8%的精神神经刺激引起的血压下降。因此，我们认为异丙酚不能完全消除TDR。提示异丙酚用于口腔手术全麻时，应适当阻断伤害性刺激。

We investigated effects of general anesthetics on trigeminal depressor responses ( TDR), which were evoked with electrical stimulation to trigeminal nerve.These studies were performed on adult Japanese White rabbits, anesthetized with urethane and alfa-chioralose. The trachea was cannulated and a catheter placed in femoral artery. Arterial pressure and heart rate were calculated from pressure wave of femoral artery. Mental nerve was stimulated with 10S train of squarewave pulses (0.5mS duration). Records of nerve activities were obtained from cervical sympathetic nerve and vagal nerve.In preliminary study, we determined that the optimal frequency and intensity range which evoked trigeminal depressor response was 5Hz and 5-20mA.In this study, mental nerve was stimulated in these manners.We examined two volatile anesthetics (isoflurane and sevoflurane ) and one intravenous anesthetic (propofol).In isoflurane and sevoflurane, degree of fall in blood pressure became smaller as inspired concentration of anesthetics became higher. TDR disappeared in almost 0.75-1.0 MAC ( tail clamp method). 1.0 MAC of tail calmp method is said to be equivalent to plane 3 or 4 of third stage in Guedel's clinical signs. It is suggested that concentration necessary to suppress TDR is rather high in isoflurane and sevoflurane.On the other hand, effects of propofol on TDR were minimum. In administration rate of 125 mg/kg/hr, which was extremely high dosage, about 8% of fall in blood pressure evoked with mental nerve stimulation was observed. So we concluded that propofol could not disappear TDR completely. It is suggested that proper blocked of noxious stimulation is necessary when general anesthesia is performed with propofol for oral surgery.